I wrote many months about about 'pump head' or 'brain fog' after surgery. I'm 27 years out, and had some concerns in the past about loss of acuity and focus. I'm not sure how much can be attributed to the surgery and how much to other factors (laziness? lack of concern about things that used to really matter? actual mental slippage?).
I DO know that six months after my surgery, I lost my job (a really good editorial/reporting job), in part, because I didn't generate as many front page stories as before the surgery.
My ability to do quick math didn't seem to change - though it isn't as good as it was, say, 40 years ago - but this is probably a result of lack of practice (hey, everyone has a phone with a calculator, don't they?). Memories of past events are very clear. Some of the most recent stuff, no quite so much.
I'm now going back to the gym, breathing better, exercising long neglected muscles, etc., and things seem - for now, at least - to be improving.
I can't say that what you may have (although I don't think you specifically SAID that you may have lost some of your previous sharpness) is certainly disturbing and scary but, as others here have noted, will probably resolve with time.